Research On Performance-based Seismic Design And Evaluation For Bridge Structures Considering Residual Displacement And Soil-structure Interaction Effects

Residual displacement could be generated due to the elasto-plastic deformation of bridge subjected to strong ground motion. As a result, bridge will be out of commission or unrepairable even though the collapse of bridge doesn't happen. Morever, because uncertain foundation soil parameters and various foundation styles, problem about siol-structure interaction is the difficuty of seismic desigen study at all times. Consequently, according to the current shortages in the seismic design and evaluation for bridges, some important ploblems are systemically studied in this paper, including performance-based seismic design considering residual displacement, seismic evaluation method considering soil-structure interaction effects. The principle contents are as follows:1. Effect of soil-structure interaction on the elasto-platic seismic response of tall and slender pier is studied. Moreover, parametric study on elasto-platic response spectra is done in order to establish elasto-platic spectra which can be in accord with Seismic Design Code for Railway Engineering. (1) By establishing an analytical model considering flexiable foundation effects, nonlinear time history analysis is carried on to study the effects of soil-structure interaction on the elasto-plastic response of tall and slender pier. (2) According to the applicable Seismic Design Code for Railway Engineering,320 strong motion records of four sites are chosen. And parametric study on elasto-plastic response spectra is done by considering parameters of earthquake motion and restoring model. (3) Elasto-plastic acceleration spetra, elasto-plastic displacement spetra and residual displacement spectra are established in accord with Seismic Design Code for Railway Engineering. So, it can provide the design spectra for performance-based seismic design for bridge considering residual displacement.2. Seismic energy response and its distributions of SDOF system and MDOF bridges are systematically study. And energy response spectra are established in accord with Seismic Design Code for Railway Engineering. (1) Based on nonlinear energy response analysis,320 strong motions are used to study the effect of parameters of earthquake motion and restoring model on seismic energy response and its distributions of SDOF system. (2) Nonlinear energy response analysis is carried on to research seismic energy response and its distributions of a double-column pier of passenger dedicated line considering soil-structure interaction. (3) Seismic input energy spetra and dissipation energy spectra are established in accord with Seismic Design Code for Railway Engineering. So, it can provide energy response spectra data for normalized parameters of cumulative dissipation energy and seismic checking method based on energy index.3. Performance-based seismic design for bridge considering residual displacement is proposed. And seismic checking method based on energy index is improved. (1) Based on Park-Ang seismic damage model, normalized parameters of cumulative dissipation energy are statistically calculated. So, equivalent ductility coefficients in accord with damage indexes are obtained. Furthermore, based on damage index, performance-based seismic design for bridge considering residual displacement is proposed by associating equivalent ductility coefficients with elasto-plastic displacement spetra and residual displacement spectra. Meanwhile, specific examples are provided to show the detailed design procedures. And the feasibility of proposed seismic design is confirmed by the nonlinear time history analysis. (2) According to seismic input energy spetra and dissipation energy spectra, seismic checking method based on energy index is improved and applied in the checking calculation for the seismic design result.4. To be aimed at Chinese bridges, improved simplified capacity spectrum method and vulnerability analysis considering soil-structure interaction effects are proposed. (1) Elasto-plastic demand spetra and strength reduction factor spectra are established in accord with Seismic Design Code for Railway Engineering. So, improved simplified capacity spectrum method is proposed by combining with the merits of ATC-40 and FEMA356. Meanwhile, proposed method is applied in a double-column pier of passenger dedicated line to do accuracy checking. (2) Based on the capacity spectrum method (CSM) considering soil-structure interaction (SSI) in FEMA440, one double-column pier of passenger dedicated line is chosen to be subject investigated. And the practicability of applying CSM considering SSI in bridge seismic evaluation is certified. (3) By combining CSM considering SSI in FEMA440 with vulnerability analysis, a new bridge vulnerability analysis considering flexible foundation effects, kinematic effects and foundation damping effects is proposed and applied in the vulnerability analysis of viaduct. By comparing with the vulnerability analysis without considering soil-structure interaction, the superiority of proposed method is confirmed.5. Nonlinear static procedures (NSP) considering the multiple-modes effects in ATC-40 and FEMA356 is improved. Furthermore, by combing with vulnerability analysis, the improved NSP is applying in seismic evaluation for super high-rise pier considering soil-structure interaction effects. And effect of multiple-modes effects on vulnerability analysis for super high-rise is studied.